JP2500957Y2 - Forward / reverse pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a connection of a drain for maintaining a low pressure in a pump case of a pump capable of forward and reverse rotation.

(Prior Art) A forward / reverse type pump that reverses the suction direction and the discharge direction depending on the rotation direction is generally provided with a drain for preventing an excessive load from being applied to the seal due to high pressure in the pump case. There is. Such a drain is connected to, for example, a suction port and a discharge port via check valves,
The hydraulic oil accumulated inside the pump case passes through the check valve according to the rotating direction of the pump and joins the low-pressure side port.

(Problem of the invention) However, in this case, when the check valve is supported in a normally closed state by an urging means such as a spring so that the discharged high pressure hydraulic oil does not leak from the check valve to the drain, the pump changes the discharge direction. There has been a problem that this biasing means sometimes resists the discharge of hydraulic oil from the drain.

In order to solve the above problems, the present invention provides a forward / reverse pump having a drain mechanism capable of smoothly discharging the hydraulic oil in the pump case while preventing the discharge oil from flowing into the drain. To aim.

(Means for Solving the Problems) The present invention relates to a forward / reverse type pump in which a suction port and a discharge port are reversed according to a rotation direction, and a drain communicating with a pump case is adjusted according to a differential pressure between the suction port and the discharge port. A shuttle valve that is connected only to the low pressure side of these is provided between the ports in the pump case.

(Operation) By connecting the drain guided by the shuttle valve from the pump case to only the low pressure side of the suction port and the discharge port, the inflow of high pressure discharge oil to the drain is blocked regardless of the rotation direction of the pump. Also, the hydraulic fluid in the drain joins the low-pressure suction hydraulic fluid without resistance.

(Embodiment) FIG. 1 shows an embodiment of the present invention.

This figure shows a trochoidal pump configured inside the pump case 4, where 1 is an external gear fixed to the rotary shaft 2 and 3
Is an internal gear that faces the outside of the external gear 1 and includes a guide ring 5
Is rotatably supported inside the pump case 4 via a central axis eccentric from the rotary shaft 1. One end of the rotary shaft 2 has a pump case 4 through a bearing 8 and a seal 10.
Rotatably protrudes from and is coupled to a motor (not shown). The other end of the rotary shaft 2 is rotatably supported inside the pump case 4 via a bearing 9.

Some oil chambers are defined between the external gear 1 and the internal gear 3 by the two tooth surfaces which are in contact with each other. The external gear 1 rotates while driving the rotary shaft 2 while pushing the internal gear 3 in the rotation direction by the tooth tips, but these oil chambers rotate due to the eccentricity of the rotation center axis of the internal gear 3. While expanding and contracting, the working oil is sucked from the suction port 6 formed in the pump case 4 in the expanding process, and is pressurized in the contracting process and discharged to the discharge port 7 also formed in the pump case 4.
When the rotary shaft 2 rotates in the opposite direction, the working oil is sucked from the discharge port 7 and discharged to the suction port 6.

The pump case 4 is formed with ports 11 and 12 that connect the suction port 6 and the discharge port to the tank, respectively, and a plug 13 is provided to close these ports 11 and 12.

Further, a drain for discharging the hydraulic oil leaking from the expanding / contracting oil chamber beyond the bearing 9 to the suction side of the pump.
14 is formed inside the pump case 4 in the extending direction of the rotating shaft 2. A shuttle valve 15 that connects the drain 14 to the suction port 6 or the discharge port 7 on the low pressure side according to the pressure difference between the suction port 6 and the discharge port 7 is housed in the pump case 4.

Shuttle valve 15 crosses drain 14 and suction port 6
And a sliding hole 17 that communicates with the discharge port 7, and this sliding hole 17
It consists of a spool 16 that fits in the slide freely. As shown in FIG. 2, the drain 14 is provided near both ends of the spool 16.
A notch 18 communicating with the suction port 6 and the discharge port 7 is formed in a groove shape in the axial direction. Further, large-diameter portions 16a and 16b are formed at both ends of the spool 16 so that the notches 18 on the seated end side are closed in a state where the spool 16 is seated at the opening end of the sliding hole 7. In FIG. 1, the upper large-diameter portion 16a is integrally formed, but the other large-diameter portion 16b forms the large-diameter portion 16b from below with the spool 16 inserted in the sliding hole 17. It is provided by caulking the lower end of the spool after fitting the annular member. The spool 16 has a sliding hole depending on the pressure difference between the suction port 6 and the discharge port 7 acting on the both ends.
The inside of 17 is slid in the axial direction to close the high-pressure side notch 18 and open only the low-pressure side notch 18.

 Next, the operation will be described.

When this trochoid pump and the hydraulic actuator driven by this trochoid pump are connected in a closed circuit, both ports 11 and 12 are closed by plugs 13, and suction port 6 and discharge port 7 are connected to the hydraulic actuator. To do. When the rotary shaft 2 is driven to rotate by the operation of the motor, the oil chamber defined by the external gear 1 and the internal gear 3 expands and contracts while rotating, and the working oil is sucked from the suction port 6 in the expansion stroke, and in the contraction stroke. This hydraulic oil is pressurized and discharged to the discharge port 7.

At this time, the shuttle valve 15 is
Is pressed against the suction port 6 side by the pressure difference between the discharge port 7 and the suction port 6, and one end of the spool 16 closes the notch 18 that connects the discharge port 7 and the drain 14. Therefore, the high-pressure hydraulic oil in the discharge port 7 is entirely supplied to the hydraulic actuator without leaking to the drain 14, and at the same time, the reflux hydraulic oil from the hydraulic actuator is sucked in the suction port 6.
Is sucked into. The other end of the spool 16 is located away from the notch 18 that connects the suction port 6 and the drain 14, and the hydraulic oil flows through the notch 18 without resistance.
Therefore, the hydraulic oil discharged from the pump case 4 to the drain 14 smoothly merges with the suction hydraulic oil of the suction port 6 through the notch 18.

On the other hand, when the rotary shaft 2 is rotationally driven in the opposite direction, the suction direction and the discharge direction of the pump are reversed and the hydraulic oil is discharged from the discharge port 7
Is sucked in and discharged to the suction port 6. In this case, the spool 16 of the shuttle valve 15 moves to the discharge port 7 side due to the pressure difference between the high pressure suction port 6 and the low pressure discharge port 7, and the suction port 6 and the drain 14 are blocked, while the discharge Connect port 7 and drain 14. Therefore, the high-pressure hydraulic oil discharged from the suction port 6 does not leak to the drain 14, and the discharged hydraulic oil of the drain 14 joins the suction hydraulic oil of the discharge port 7 without resistance.

When the hydraulic actuator is driven in an open circuit, the return hydraulic oil of the hydraulic actuator is returned to the tank, the plug 13 of the port 11 is removed, and the port 11 is connected to the tank. When rotating the pump in the reverse direction, the port 11 is closed by the plug 13, the plug 13 blocking the port 12 is removed, and the port 12 is connected to the tank. Even in the open circuit, by opening and closing the ports 11 and 12 in this manner, without using a check valve as in the closed circuit,
While preventing discharge oil from flowing into the drain 14,
The discharged hydraulic oil can be smoothly merged into the suction side.

(Effect of the Invention) As described above, in the present invention, since the drain valve communicating with the pump case is connected only to the low pressure side of the suction port and the discharge port,
The discharge oil is prevented from flowing into the drain regardless of reverse rotation, while the hydraulic oil discharged to the drain joins the suction side without resistance. Therefore, with a simple configuration, the inside of the pump case can be constantly maintained at a low pressure, and the pump can be operated in a preferable environment.

Further, according to the present invention, since the shuttle valve is provided in the pump case so as to be located between the suction port and the discharge port, the structure of the passage for leaking oil leakage is simplified to reduce the size and weight of the pump and reduce the cost. Can be realized. Of course,
The present invention can be applied to any pump capable of forward and reverse rotation.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a forward / reverse trochoid pump showing an embodiment of the present invention, and FIG. 2 is an external perspective view of a shuttle valve spool thereof. 1 ... External gear, 2 ... Rotating shaft, 3 ... Internal gear, 4 ...
… Pump case, 6 ... Suction port, 7 ... Discharge port, 11,12 ... Port, 13 ... Plug, 14 ... Drain, 15 ... Shuttle valve, 16 ... Spool, 18 ... Notch.

Claims (1)

(57) [Scope of utility model registration request] 1. A forward / reverse type pump in which a suction port and a discharge port are reversed according to a rotation direction, the pump is located on the axis of the suction port and the discharge port formed in a straight line in the pump case and between the both ports. The shuttle valve is arranged in this way, and the drain that communicates with the pump case is connected to this shuttle valve.The shuttle valve switches according to the differential pressure between these ports, so that the drain oil in the case drains the shuttle valve. A forward / reverse type pump characterized in that it flows out to the low pressure side through the pump.